Description of Appendix Table 1
Pennsylvania "DOT" Tailgating Treatment (Experimental)
Comprehension Time: 5 sec
P/R Time: 2.5 sec
Adjustment Time: 20 sec
Following Time: 2 sec
Effective Time: 60 sec
Vehicle Correction: 15 ft
| Posted Speed (mph) | Posted Speed (fps) | Distance Travelled (ft) | S, Marking Spacing (ft) | Minimum # Markings in Pattern | L, Min Pattern Length (ft) | X, Pattern Spacing (ft) |
|---|---|---|---|---|---|---|
| 25 | 37 | 73 | 60 | 18 | 1020 | 2200 |
| 30 | 44 | 88 | 75 | 18 | 1275 | 2640 |
| 35 | 51 | 103 | 90 | 17 | 1440 | 3080 |
| 40 | 59 | 117 | 105 | 17 | 1680 | 3520 |
| 45 | 66 | 132 | 115 | 17 | 1840 | 3960 |
| 50 | 73 | 147 | 130 | 17 | 2080 | 4400 |
| 55 | 81 | 161 | 145 | 17 | 2320 | 4840 |
| 60 | 88 | 176 | 160 | 17 | 2560 | 5280 |
| 65 | 95 | 191 | 175 | 16 | 2625 | 5720 |
Diagram
A diagram is shown with two car symbols in line with two oval dots. The distance from the center of one dot to the center of the other is labeled "S".
A pattern of seven dots in a straight line is shown, with the distance from the center of the first to the center of the last labeled "L".
Two series of seven dots each are shown in a straight line with a gap between the two series. The distance from the center of the last dot in one series to the center of the first dot in the next series is labeled "X".
Definitions
Comprehension Time (sec): Amount of time required for driver to comprehend the meaning of the markings.
P/R Time (sec): Indicates Time required for an average driver on target roadway to perceive that an action is required and to begin that action. Typical Value is 2.5 seconds.
Adjustment Time (sec): Amount of time provided for the following driver to gauge and adjust the Distance between their vehicle and the lead vehicle.
Following Time (sec): The enforceable following time for target roadway. Vehicles should travel a Distance apart from each other such that this Time has passed for a following vehicle to reach the location of the lead vehicle at Time t0.
Effective Time (sec): Length of Time for which the pattern maintains an effect on the driver. Relates to how long the driver can maintain the Distance corresponding to the Following Time after leaving the pattern.
Posted Speed (fps): Relates to the Posted Speed Limit on the target roadway.
Distance Traveled (ft): At the given Posted Speed, this indicates the Distance the vehicle will travel in the Following Time. Value is Posted Speed (fps) times Following Time (sec).
Marking Spacing, S (ft): This Distance reflects the spacing between two pavement markings within the pattern such tat vehicle will traverse two markings in the Following time. Value is equal to Distance Traveled (ft) rounded to the next 5 foot length less the Vehicle Correction.
Vehicle Correction (ft): Distance vehicle must be away from the nearest DOT to allow the DOT to be visible from the drivers eye position. Value assumed to be 15 ft measured from bumper to edge of DOT marking.
# Markings in Pattern: The number of markings at the Marking Spacing that can be placed in the length of roadway required to travel at the Posted Speed for the total required Comprehension, P/R, and Adjustment Times. Value is that length (ft) divided by marking Spacing (ft).
Pattern Length, L (ft): Distance from the center of the first making in the pattern to the center of the last marking in the pattern. Value is the Number of Markings, less one, times Marking Spacing.
Pattern Spacing, X (ft): Distance a vehicle will travel between Marking Patterns. Relates to Effective Time such that the effect of the previous set of markings will just begin to fade as driver encounters the next set. Value is Posted Speed (fps) times Effective Time (sec).
